Purpose: The current study addresses a gap in the literature regarding syntactic development of adolescent boys with fragile X syndrome (FXS) and Down syndrome (DS). Specifically, we ask whether syntactic skills plateau or continue to change during adolescence for these groups and whether the profile of syntactic change differs between boys with…

De novo events appear more common in female and simplex autism spectrum disorder (ASD) cases and may underlie greater ASD risk in older fathers' offspring. This study examined whether advancing paternal age predicts an increase in simplex (n = 90) versus multiplex ASD cases (n = 587) in 677 participants (340 families). Whether or not controlling…